Steam generating system



Dec. 26, 1933. J. c. COUTANT STEAM GENERATING SYSTEM 4 Sheets-Sheet 1 Filed Nov. 20, 1930 INVENTOR, 5% M W.

ATTORNEYS.

Dec.'26, 1933." J. cs. COUTANT 1,940,663

STEAM GENERATING SYSTEM Filed Nov. 20. 1930 4 Sheets-Sheet 2 l J7 Q Q Q 83a" INVENTOR ,0. 3 a Y QwSLaL 7 BY ATTORNEYS.

Dec. 26, 1933. J. G. COUTANT STEAM GENERATING SYSTEM Filed Nov. 20. 1930 4 Sheets-Sheet 5 INVENTOR We MM KIM A TTORNEY S.

Dec. 26, 1933. J7 5. COUTANT 1,940,663

STEAM GENERATING S YSTEM Filed Nov. 20. 1930 4 Sheets-Sheet 4 J 7 T L My #0 I I //0 //.9

INVENTOR,

BY W -firM/U ATTORNEYS.

Patented Dec. 1933 I UNITED STATES PATENT OFFICE STEAM GENERATING SYSTEM Jay Gould Coutant, New York, N. Y.

Application November 20, 1930, Serial No. 496,870, and in France November 22, 1929 8 Claims. (or. 122-33) This invention relates to steam generating sys- The results described cannot be obtained with tems, such as are used in various fields, for exknown modern high pressure boilers for the folample for power houses or other stationary uses, lowing reasons. (a) It is the present practice to for locomotives, or marine uses, and for various locate the boiler in a new building space or else purposes, particularly for supplying steam to the old low pressure boiler is removed to provide 80 drive steam turbines or other forms of engines. space for a high pressure unit. (b) Old boilers One important feature of this invention is the are usually replaced by a steam reheater made generation of steam under a succession of difierin the form of a superheater which receives exent pressures, in which aspect it is herein referred haust steam from the high pressure turbines, and to as a multiple pressure steam boiler or genwhich has not any thermal storage such as a erator. drum, and resulting in fluctuations in tempera- The main object of the invention, in this aspect, ture and pressure. (0) The change from old is that central power station boilers, including boilers to reheaters involves a complete change those existing in use, may beimproved to deliver in piping, which is a substantial expense. (d) dry steam simultaneously at difierent and pref- Steam reheaters with the usual high pressure erably constant pressures, and at substantially boiler arrangements require distilled water, and maximum temperatures, as may be required for therefore involve the additional expense of econexample with the employment of high, intermeomizers and evaporators; (e) Known high presdiate and low pressure steam engines or turbines. sure boilers have large tubes, with thick metal A secondary objectis to aifordcontinuous servwalls, required for natural water circulation for ice with ordinary feed water conditions, by avoid: carrying away heat. As the tube wall thickness ing the necessity of taking the boiler out of servincreases, it is essential to provide more difiusion ice for cleaning. of radiant heat and reduction of heat absorption,

The multiple pressure steam boiler of this into prevent overheating of metal. Therefore it vention may occupy only the same space as an is necessary to locate such bare tubes a great 0 r i ry r. wh y t pr in as much as distance from flame or to cover with cast iron; twice the weight of steam, and supplying the tursuch arrangements being usually highly costly bines with four times the energy. It may be inand afi'ording only an absorption of a portion,

stalled as hereinbelow disclosed so as to require say one-half, the amount of heat. (I) It is cussubstantially no increase of flue area, or of intomary with present high pressure boilers to 1116 draft p y. 0f chimney for handling evaporate water in tubes directly exposed to rathe increased weight of gases, which will beat diant heat of the fire, using distilled water, to lower temperatures. avoid scale formations, while leakage of con- Oth obj c a t ad a of e invention densers sometimes causes poor boiler feed water, are the elimination of feed water evaporators compelling taking th b il r t f service for and heaters, also the substitution of air preheatcleaning, (g) Natural ir l ti i high presers for economizers. These objects are accomsure boilers and water walls often results in over- D d for a ple by feeding raw water to a heating of metal by local intense heating, where lower Pressure drum Standing a P e of the water evaporated does not change the difier- 5 kilogi'ams D Square centimeter) Where i is ence in static head or hydrostatic head suflicient evap fi m be later utilized and bled from to cause circulation. (h) High pressure steam is turbines or condensed; and then feeding it to a usually superheated below t of the low presfrom turbines or condensed, and then supplying a 1 9 drum cm) where sure steam temperature, otherwise the metal tem- 1s agam evaporated later utmzed and bled perature would be higher, due to steam pressure under the same flow conditions. (2') Boilers pmtion of it to a super high pressure drum (150 using forced circulation consume power for the i zm r t hih wall 5 ififiis g sfififi itig i circulating at all times, and if the pump stops, caused to flow by an induced fomedsystem of due to, acc dent, the boiler tubes become overcirculation through water walls and slag screen, e All whlch pe that afford maximum radiant heat absorption per 11ml clrcmatlon f 1eanh 1g at lfegulal squ-are t of n surface 11 of these rails, and the taking of the boilers out of service. vantages and actions are for obtaining the maxi- It i an Object this invention to afford a mum efliciency and affording the largest return on practical boiler of several pressures or stages money t d, which will overcome the many objectionable feapumped from turbine bleeders.

turbines is wet and cannot be reheated in a superheater without causing great fluctuations in temperature. Therefore, it is the plan of this invention to employ a steam drum for each pressure, for the purpose of drying the steam and f maintaining uniform pressures and temperatures;

The high and low pressure drums being say half filled with water receive the exhaust from iihe super and high pressure turbines, which exhaust enters the drums below the water level. The level of water in the several drums may be maintained as desired by any known means of boiler feed regulation.

Second-The use of small diameter tubes with thin metal walls in which the fluid is circulated mechanically by an induced-forced circulating system that utilizes distilled feed water The small tube construction forms the furnace, including water grate at bottom, top slag screen, and water walls, allowing continuous operation as it is not necessary to take'the boiler out of service for cleaning. It also permits the maximum radiant heat absorption per square meter of wall surface,

and therefore permits more fuel to be burned per cubic meter without slagging of ashes on the boiler tubes, which results in a great in= crease or even doubling of steam production, thus increasing the energy supplied to turbine, and enables continuous operation.

Third-The super pressure boiler may consist of a drum and thin metal small diameter tubes in which water is mechanically circulated by an induced-forced system, constructed for pressures of say 150 kgs. per sq. cm. It supplies steam to a heat exchanger consisting of a drum with a part containing heating coils; the drum being half to three quarters filled with water pumped from turbine bleeders. The super pressure steam circulating through the coils generates steam at high pressure, say 100 kg. per sq. cm the super pressure steam being partly condensed-or pumped back to the boiler,.-while a small amount of steam taken from the return after leaving the heat exchanger, is utilized for driving the induced-forced circulation pump, and it.exhausts into the succeeding low pressure drum; therefore, the actual cost of circulation is Fourth-"The induced-forced mechanical system of circulation may be employed during forced operation, making it unnecessary to 0perate the circulating pump at all times, also, in case of accident to the pump, water will fiow, due to natural circulation, and there is not any immediate danger from overheating of the tubes.

Fifth-The invention may be practiced by use of existing boiler drums-and of the piping to turbines, without any change. Some of the boiler heating surface may be removed, and that which remains placed above the top slag screen, in a position where it will not receive intense heat. Therefore, raw water can be fed to the drum and evaporated in the heating surface without forming scale; and solids deposited in the mud drum may be blown off. This arrangement eliminates evaporation and assures continuous operation of the boiler, avoiding periodical cleaning. The existing boiler drum, being say half filled with water, may receive the'exhaust steam from the high pressureturbines below the water line, and

it serves asa heat accumulator, taking up fluctuations ahd delivering dry steam to the superheater at constant pressure.

iS'ixthri' -The amount of heating surface in existing boilers is purposely made small to allow high pressure steam tofiow through a high pressure superheater at light loads, passing directly into tpe low pressure boiler drum below the water gvel, generating steam. This will not homeessary at heavy loads, and will be cut off automatically by a valve. A purpose of this invention is to allow steam to flow through a high pressure superheater at all times, to avoid overheating of the superheater tubes, but principally to obtain higher temperature high pressure steam, since by the arrangement the superheater can be located in a zone of more intense heat.

This invention includes the process of generating steam utilizing multiple boiler pressures, with circulating systems that ensure continuous operation with ordinary boiler feed water, increasing'the steam production and energy output per unit volume of space occupied and at a substantially lower cost.

Other and further objects and advantages oi, the present invention will be explained in the following description of embodiments thereof, or will be understood to those skilled in the subject.

In the accompanying drawings Fig. l is a general diagrammatic elevation or vertical section of a steam boiler or generating apparatus of a type available for central power station purposes and embodying the present invention.

Fig. 2 is a vertical section of a detail, namely the device for causing mechanically inducedforced circulation at high rates of steam output but allowing natural circulation at low rates of output, applied for example for the return oi condensate from the heat exchanger.

Fig. 3 is a vertical section and elevation of a circulation device, giving similar action, but being applied for the circulation of boiler water through the water grates, water bottoms, top slag screens and furnace side walls.

Fig. 4 is an elevation of the device shown in in Fig. 5 looking from the left side.

Fig. 7 shows a modified application and embodiment of the present invention, embodied in this case in a locomotive, the same being shown in diagrammatic elevation and vertical section. Fig. 8 is a transverse vertical section taken substantially on the plane 8-'-8of Fig. 7.

Referring first to the embodiment of Figs. 1 to 6, this construction is especially adaptable to power plants. One condition that prevails throughout power plant equipment is that through each element of apparatus there is a more or less continuous flow of one or more fluids, water or steam, under pressure and'at-elevated temperature. This invention is based on control and arrangement of flow of fluids at elevated temperatures and pressures in a manner developed from the relations observed during operations. Another factor involved is that the real purpose of circulating water in tubes exposed to the fire is for conveying heat from a hot location to a remote and relatively cool zone. It has been If the speed can be increased mechanically sumclently, beyond natural circulation, this will avoid danger of scale formation in the tubes. Another consideration utilized herein is that radiant heat intensity delivered to and absorbed by bare circulation tubes will be less as the wall tube thickness is increased. With these factors in mind, the multiple pressure boiler of this invention may be constructed and function as follows.

Fig. 1 shows two usual drums C and D and two supplemental drums A and B, as an illustrative mode of embodying the invention. The drum A carries distilled water and steam under super high pressure, fed with hot water, for example by pipe 12 from a super pressure turbine exhaust. The drum B is a heat exchanger and carries water and steam at high pressure, and delivers to a superheater for consumption. The drum C is a low pressure drum fed by ordinary feed water and delivering for consumption. The drum D is at high pressure, and may act as a steam accumulator and being fed with distilled water, for example from the super pressure turbine.

Referring first to the combustion system, pulverized fuel may be supplied at regulated rates through a fuel pipe 1 to a pilot burner 2, which is supplied with combustion air through a pipe 3, the two being mixed at the burner 2 and pro jected into the combustion pilot chamber 4 where it is ignited and burns instantaneously at highest possible temperature, above the ash melting point, and maintaining the ash from the fuel in a fluid state, so that it can be allowed to how out continuously or tapped periodically, for example, into molds to produce blocks.

The combustion in chamber 4 aifords a pilot flame for the main combustion, for example of pulverized fuel, supplied through fuel pipe 5 at controlled rates to a main burner or system of burners 6, supplied with combustion air through duct 1'. Thea-i1 and fuel mix in the burner and the mixture is projected into the furnace 8, where it ignites and burns almost instantaneously with a clear flame, giving a clear atmosphere in the furnace, which permits the maximum transfer or diffusion of heat by radiation to the heat absorbing surfaces, namely the water grate 9, water walls 10 at all sides and top slag screen 11, all oi which elements preferably constitute the heating or steam generating surface of the superhigh pressure portion of the apparatus.

The super pressure portion comprises the drum A, about half-filled with distilled water received from so-called bleeders of the turbines or engines.

This hot water under pressure is led by pump 12" into the drum by a feed pipe 12 which distributes the water in the drum. The heating surface 9, ill and 11 is constructed of metal tubes of small di: ameter and thin walls, which are able to absorb heat at a faster rate than can be carried away by natural circulation which is impeded by the small internal area, and high friction. l have therefore provided mechanical circulation, and in a way to afford a system that provides some circulation at all times. What 1 term an induced forced circulation system is preferably embodied in this invention for the purpose. For example, some water is taken from drum A through a pipe 13 to the inlet of a pump 14, which creates a forced flow and pressure in pipes 15 and 15 connected respectively to internal distributing pipes 16 with nozzles 17 opposite each tube or the grates 9 or of the walls 10, within headers 18 and 18 respectively, as seen in Figs. 1, 3 and ll.

Part of'the water from drum A may be conducted through pipes 19 to supply and completely fill the headers 18 with water by natural circulation. water at high velocity into the tubes 9 or 10 induce water flow from the header, received through pipes 19, and force it into the tubes, thus giving a very high rate of circulation, and liberation of steam in the drum A above the water level.

It is desirable to permit flow toward the boiler in case the pump becomes inoperative. The pump 14 being of the centrifugal type permits through circulation it it should cease rotation.

The pump 14 imposes a forced rapid recirculation upon the ordinary gravity recirculation which is afiorded by the downtakes 19. With the present invention the forced rapid recirculation comprises a second downtake or set of downtalres 13 from the water space in the overhead drum A, these extending directly from such water space so as to be under direct hydrostatic pressure from the water in the drum, and leading to the force pump. This force pump it will be noted is at a low level, substantially adjacent to the level of the lower ends of the exposed water tubes of the-boiler, meaning substantially not higher than such level, and in no case as near to the level or" the overhead drum A as to the lower ends of such exposed tubes. The force pump receives the recirculated water under the direct hydrostatic pressure of the drum, plus the entire height of the downtakes 13, so that the pump is supplied with water in ample volumes at a substantially great hydrostatic pressure, which is of advantage in the operation of the pump. The force pump dis charges through the several delivery pipes 15 and 15 and through the nozzles 13?, one for each exposed boiler tube, thus forcing recirculation at substantially equivalent high rates through all such exposed tubes, .this forced recirculation arrangement serving supplementally to induce enhanced recirculation through the first or gravity downtalres ill.

The super pressure steam leaves drum A through a dry pan or element in a dry state, and thence passes through pipes as leading to heating coils 21 located in the high pressure drum 7-3,, which is preferably maintained about threefourths filled with water. The super pressure steam, say at 150 kgs. per sq. cm., generates steam by heat exchange in the drum 23, say at ldll'lrgs. per sq. cm. pressure. partly condenses in the coils and this condensate is drained, with some steam, through pipe 22. The steam isseparated and taken off at a separator 22 and is shown used for driving certain circulating pumps. This super pressure steam is shown passing by pipe 22* to a pump 23 and by extension 22 to the pump 14 for operating them. Some or the water from the separator 22 is passed by pipe 24 through the pump 23, and discharged at high velocity through a pipe 25, which induces forced flow of steam and water from pipe 26 descending from the separator, and forces all such water into a pipe '27, which delivers into the pipe 13 leading to inlet of pump 14. it will be seen that this arrangement of pump 22- is auxiliary to the'pump l4 and is not absolutely neces- -The nozzles 17, 'd'scharging pumped,

The super pressure stearu llil sary, but may be desirable under certain conditions to ensure maximum circulation.

The heat-exchanging drum B may be fed with hot water from a turbine or engine exhaust, represented by inlet pipe b, and this drum is heated by the super pressure coils 21 and the water evaporated into high pressure steam adapted for consumption, preferably after traversing a superheater, as will be further on described.

Coming next to the low pressure portion of the boiler, the drum C, which may be a preexisting drum, is shown supplied with raw feed water through a longitudinal distributing pipe 28. From the drum C the water may flow down a pipe 29 .-to certain boiler headers 30, which are connected to heating surface boiler tubes 31, which slant upwardly and in which the water is evaporated and discharged to upper headers 32, connected by tubes 32 to carry steam to the drum C, above the water level therein. The conventional type of tubular boiler is shown in Figs. 1, 5 and 6 as divided substantially into two boilers, in a sectional manner, the tubes 31 and headers 30 and 32 being alternated with other tubes 38 and headers 37 and 39 to be described.

The heating surface or tubes 31 is not exposed to the very intense heat and is therefore not subject to the formation of scale. Solids in suspen-' sion in the water precipitate in mud drum 33 and are blown oif methodically through pipe connection and valve 34.

The existing high pressure portion of the boiler, namely drum D is herein arranged as follows. 'It is shown supplied with water from a suitable source, as the super pressure turbines, namely with exhaust and water drained from the bleeders of the turbines, forced by pump 35* through a feed pipe 35 delivering into the drum. This is distilled water; free from contamination, and therefore assures continuous service. The drum D is preferably half filled with water. From the drum water flows down by pipes 36 into lower sectional headers 3'7, which are connected to heating surface tubes 38, discharging to upper sectional headers 39, which in turn are connected back to the drum D above the water level by pipes 40, which liberate in the drum the generated steam. The headers and tubes 3'7, 38 and 39 are alternated with those 30, 31 and 32 already described, giving independent circulating systems combined in one tubular boiler.

The high pressure circulation tubes are preferably made small in diameter to avoid having thick walls, so that the amount of heat absorbed per second is more than natural circulation can carry away, due to friction and small internal area of tube. With this invention some of the water is drawn from drum D, through a pipe 41, leading to the inlet of a pump 42, which discharges at high pressure throughpipe 43, which is connected to a distributing header 44 with nozzles 45, opposite the tubes 38, as indicated in Figs. 5 and 6'.

.The high velocity discharge of water from the nozzles 45 into the tubes induces and forces a greater quantity of water through the tubes, thus conveying fluid and heat at a very rapid rate away to a remote point, on the principles described. j

The high pressure steam, say at-100 kgs. per sq. cm. which is generated in heat exchanger drum B, together with that generated in drum D, is conducted bypipes 46 and 46 respectively to a collector, 46, which by pipe 46 delivers steam to the inlet 47 of a superheater 48,- its outlet 49 delivering by pipe 49 to turbine or point of consumption. A valve 50, arranged in a pipe 51 branched from pipe 49 operates similarly to a safety relief valve, and allows steam to flow through superheater at all times, and it may discharge into low pressure drum C. The drop in pressure between the superheater inlet and outlet, when steam is being used by a turbine, will be sufficient to cause the relief valve 50 to close, while when the turbine is not using steam the pressure in pipe 49 will rise to the full pressure, and the relief valve being so adjusted will permit the high pressure steam to flow through the pipe 51 to the feed'pipe 28 of the drum C. This may generate steam in drum 0 at say 25' kgs. per sq. cm., which will permit higher temperature steam to be generated in and delivered from the high pressure boiler, or drums B and D, as the super- 7 heater. tubes will be protected from becomingoverheated. The waste gases, after leaving the described multiple pressure boiler, may be passed into an air preheater 52, shown conventionally, where some of the heat is recuperated' and utilized for combustion. The gases then pass into a gas cleaner, 53, where the dust and moisture may be precipitated and removed and the reduced volume of cooled and contracted gas is passed through an induced draft fan 54 and delivered to a stack 55.

Figs. '7 and 8 show an application of the improvement to a vehicle or locomotive, wherein the usual drum or steam space C" is supplemented by a pair of super pressure drums A, A and a high pressure drum B acting as a heat exchanger, or evaporator. The drum 0' may be the steam space of a'fire tube boiler, with fire tubes C delivering the gases to a forward flue or box 156 and stack 155.

An oil burner 106 is shown delivering into the firebox or combustion chamber 108, havingclosed side walls comprising circulation tubes 110, the upper parts 110 of some of which are crossed J over to form a closed water ceiling protecting the drum B, while the forward tubes'are extended and shaped as at 111 to serve as a protecting screen for a high pressure superheater 148 to be described. V

Flor certain purposes the equipment may comprise a steam turbine or turbo-generator 157, the current from which may-be employed for any desired purposes,forexample for operating electric motors applied to the driving of the wheel. axles of the locomotive or cars of the train, a motor 157- being indicated as representative thereof. The exhaust from the turbine 157, or fluid bled therefrom, may be conducted through pipe 112 to the super pressure drums A; The drums A, A may be supplied also by condensate from acondenser and feed water heater 158, from which leads a pipe 158 for this purpose.

The locomotive however may comprise the' usual reciprocating engines of high and low pres to the fire tubes C of the low pressure boiler or drumC', thence by way of the flue or box 156 to the stack 155. By providing quick, complete 15 livering into the super pressure drums A, A.

The circulation may be on the same principles as explained in connection with l 'igs. l-E, and preferably the induced-forced circulation system is employed at the corresponding points. Thus a certain amount of water is drawn from the lower sides of the drums A through pipe 113 and conducted to the inlet of a pump 114, which creates a forced flow and pressure within pipes 115 connected to interior distributing pipes 116 having nozzles 117 directed into the respective side wall tubes 110, the pipes 116 being enclosed centrally within larger pipes or headers 118. As before stated the fluid circulating upwardly through the tubes 110 delivers back into the drums A, thus completing the circulation. There may be a direct supply or descent of water from the drums A through pipes 119 which are capable of completely and quickly filling the headers 118.

The high pressure drum B is in the nature of a heat exchanger operated by the super pressure steam from the drums A. This steam is, taken out of drums A by pipes 120, one at each side,

these leading to a distributing pipe 120' which.

enters the upper part of the drum B and delivers the super pressure steam to a system of heat exchanging coils 121, in which the steam will condense or partly condense, giving up its heat through the walls of the tubes and thereby evaporating the water contained in drum The super-pressure in drums A may for example be 150 kg. per sq. cm, which may develop in drum E a pressure of kg. per sq. cm, referred to as high pressure.

The fluid passing out from the coils 121 isconducted by pipes 122 to a steam separator 122 the steam being taken off at this point thus keeping up the steam flow through the heat exchanger coils 121, and then utilized to induce aforced flow toward the boiler by driving the pump list, as with Figs. 1 to 6.

The steam at high pressure generated in the drum B may be drawn off by a dry pipe near the top and conducted by pipe 14,6 to the inlet 147 of a superheater 148 placed in the path of the flames leaving the firebox. The outlet 149 of the 'superheater connects with pipe 1% in which is placed a relief valve 150, in the nature oi'a safety valve, which, when the pressure is maximum opens to deliver steam by way of pipe 151 directly into the low pressure drum C. By this means the superheater is continuously maintained in operation. In the pipe l l9 is shown also a throttle 149 which may be controlled from the cab. The pipe 149 conducts the high pressure steam to the point of consumption, namely to the high pressure engine 159, or to the turbogeneratcr 157, or both.

The high pressure engine and turbine therefore are operated by high pressure steam, namely 100 kg. per sq. cm. while the low pressure engine loll is operated by the low pressure steam from the drum C at about 25 kg. per sq. cm. The exhaust of the high pressure engine is shown as conducted by pipe 128 into the low pressure drum C, which constitutes a low pressure boiler or the fire tube type. The steam outlet from the drum C may be through pipe 128 in which is included a throttle valve 161. Interposed in this pipe is indicated a low pressure superheater 162 consisting of tubes extended reversely through some of the fire tubes C the outlet of the superheater being connected'by pipe 128 directly with the valve box of the low pressure engine 160. The low pressure engine is shown as exhausting through a pipe 163 located in the flue box 156 and directed into the stack 155.

As a special feature there is herein shown a locomotive which is adapted to be operated for short runs without the use of fuel, for example where electric current is provided by overhead conductor or third rail, at the same time without shutting off on the operation of the steam plant of the locomotive, or allowing it to cool down. This is of particular value in the bringing of passenger trains into and out of terminals, giving the very great advantage of avoiding the necessity of changing engines at a designated dis tance from the terminal. This part of the in vention operates on the principle of utilizing the electric current as a means of generating heat .to maintain the boiler system in operation, so that the locomotive can run on its own steam. Preferably electric heating units 175 are embod led within the high pressure boiler B, in close proximity to, or alternating with the heating tubes 121 therein. This is preferable to placing the'electric heating means within the super pressure drums A, and operates to generate directly the steam required for the high pressure engine or turbine. It is only necessary to cut off the flow of fuel or oil to the firebox 108, giving instantaneous relief from smoke, after having turned the line current into the heating units 175, which should be predetermined to develop heat sufficient to generate steam in the drum B at approximately the normal pressure of say 100 kg. per sq. cm., although a lesser heat and pressure would be serviceable and sufiiciently practical for the purpose, considering the great delay which is avoided by not having to change engines.

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Fig. 7 indicates an overhead conductor 175 7 it off, and regulation of action may be secured by periodically openingor closing the circuit, or by rheostat. The circuit is completed by wire 181 from the other terminals of the heating units to a ground point, indicated as the axle of a wheel.

In one aspect the present invention may be described as a steam generating system including certain combinations or subcombinations of coop crating elements. First, the super pressure drum hand the heating surfaces delivering to it con stitute a super pressure boiler, the surfaces 01 which are heated by the hottest exposure to the lire. Second, the drum B constitutes a high pres-. sure boiler having surfaces'heated by the outgoing steam from the super pressure boiler and has a steam outlet delivering to a point of con= sumption such as a high pressure turbine or other engine. Third, this combination of first and sec= 0nd elements is believed to be new when combined with means for forcing rapid circulation through the super pressure boiler and its heating surfaces, these preferably constituting a substantially closed circuit and using distilled water. Fourth, the described combination is of greater utility when comprising also a low-pressure boiler, consisting for example of the drum C and the heating surfaces delivering to it, heated by the less intense or more remote exposure to the fire, this boiler having a steam outlet to a point of consumption separate from that ofthe high pressure boiler. r A combination feature of substantial importance is that while the exposed heating surfaces or tubes of the low pressure boiler may be ordinary boiler tubes; relatively thick, those of the super pressure 'boiler are preferably thin walled and relatively small in diameter, so as to absorb and convey to the circulating fluid the 'maximum quantity of heat pvithout danger of of consumption. The use of the"described means of forced'circulation not only allows for natural circulation at light loads, but also insures the continuation of flow in case of stoppage of the pump, thus protecting the boiler from overl valve beyond the superheater adjusted to remain open when substantially the full boiler pressure is delivered from the superheater, in other words when consumption is subnormal, the opening of this valve permitting the superheater to be maintained under circulation, together with the entire high pressure boiler system; and the steam discharged from the relief valve may be advantageously used, for example by delivery into the drum of the low pressure boiler.

Seventh, the complete combination illustrated in Fig. 1 embodies a second high pressure boiler with heating surfaces feeding to drum D, this boiler delivering to the same superheater, and outgoing steam pipe as the high pressure drum B. This boiler may be a forced circulation boiler, and as it supplements the output of drum B, both the drums B and D may be made of smaller diameter than otherwise, with proportionately high strength.

In the complete combination the small amount of distilled water exhausting from the circulating pumps of super pressure boiler may be supplied to any of the drums B, C or D. The exhaust from the pump associated with drum D may be fed to the low pressure drum C. Preferably mainly raw water is fed to drum C, whereas drums B and D may use either raw or distilled water obtained from the turbines or otherwise, and the super boiler employs distilled water in a substantially closed circuit, the supply maintained from a turbine to insure the indicated water level in the drum A. Substantially similar considerations apply to the locomotive embodiment of Figs. 7 and 8 wherein however there is no boiler or drum indicated corresponding to D of Figs. 1-6.

The complete apparatus delivers simultaneously high pressure steam and low pressure steam, for

example to high and low pressure turbines, and by the operation of this invention the maximum temperature and pressure for each boiler maybe constantly maintained, to the great advantage of the operation of the power station. The use of the relief valve 50 makes possible the same high temperatures for both steam deliveries, while the valve avoids overheating of the drum B and superheater by maintaining a flow of steam therethrough to.cool them.

The formation of scale is prevented through-' out, In the low pressure boiler the evaporation is at a temperature below that at which scale is formed. In the high pressure boiler D the forced circulation system gives velocities at which scale will not form. In the super pressure boiler the use of distilled water, in a closed circuit, assures continuous service without formation of scale. Therefore it is unnecessary to take the boiler out of service for cleaning of scale, and feed water evaporators and conomizers may be dispensed with. V

The super pressure boiler is enabled to take away the maximum amount of heat per unit time, by the use of exposed tubes ofsmall diameter and thin walls, permitting maximum absorption by radiation, coupled with high speed circulation continuously conveying away the absorbed heat to a remote part of the system.

The need of auxiliary power to operate the usual feed pumps is practically eliminated by the described circulation system involving pumps operated by a small fraction of the super pressure steam to drive distilled water into high pressure portions of the boiler.

The combination including the drum D and connected boiler is of advantage in that said boiler acts as an accumulator of steam or heat. The presence of the steam supply in the drum D. at high pressure and temperature, gives a steadying action supplementing the delivery of stay from the drum B, so that substantially constant pressure delivery can be relied on. e

. In various boiler drums are indicated wire meshes or gratings at about the designated water 130 levels to minimize water turbulence and splashing or spraying into the outgoing steam.

Having thus described particular embodiments as illustrative of the principles of the present in-' vention it is tobe understood that the invention is not intended to be limited to the detail features as disclosed in said embodiments except to the extent set forthin the appended claims.

What is claimed is: I v

1. In a steam generating system a super pressure boiler having surfaces heated by the radiant exposure to the fire, a high pressure boiler having surfaces heated by the outgoing steam from the super pressure-boiler, means for forcing rapid circulation through the super pressure boiler and its heating surfaces and a steam outlet from the high pressure boiler to the point of consump on;

the super pressure boiler comprising a drum, and

the high pressure boiler comprising a second 1g;

drum containing a heat exchanging coil, a steam connection from the first drum to said coil, a

steam separator a water .connection from the coil to said steam separator, and a water connection from said separator to the super pressure boiler 35 infeed, a direct connection from the first drum to said infeed, pump means for forcing the water through the infeed into the super pressure boiler, and a steam connection from the I separator for operating such pump means. Q

ing rapid recirculation through the super pressure boiler, and its heating surfaces supplemental to its gravity recirculation, and a steam outlet from the high pressure boiler to the point of consumption; the super pressure boiler comprising a drum, and the high pressure boiler comprising a second drum containing a heat exchanging coil, a steam connection from the first drum to said coil, a water connection from the coil to the super pressure boiler infeed, a direct connection from the first drum to said infeed, pump means for forcing the water through the infeed into the super pressure boiler, and a steam connection for operating such pump means.

3. A system as in claim 2 and wherein is a forced-induced-fiow nozzle between the pump means and the boiler, and a gravity connection from the first drum to the header space adjacent said nozzle for induced feed during forced feed and for gravity feed otherwise.

4. In a steam generating system a super pressure boiler having surfaces heated by the hottest exposure to the fire, a low pressure boiler having surfaces heated by less intense exposure to the fire, a high pressure boiler having surfaces heated by the outgoing steam from the super pressure boiler, means for forcing rapid circulation through the super pressure boiler and its heating surfaces and steam outlets from the high pressure and low pressure boilers respectively to separate points of consumption; together with a second high pressure boiler or accumulator, having heating surfaces exposed to the less intense heat of the fire, means for forced circulation therethrough, and a steam outlet delivering supplementally to that from the first high pressure boiler.

5. In a steam generating system a super pressure boiler having surfaces heated by the radiant exposure to the fire, a high pressure boiler having surfaces heated by the outgoing steam from the super pressure boiler, means for forcing rapid circulation through the super pressure boiler and its heating surfaces and a steam outlet from the high pressure boiler to the point of consumption; together with a'second high pressure boiler or accumulator, having heating surfaces exposed to the less intense heat of the fire, means for forced circulation therethrough, and a steam outlet delivering supplementally to that from the first high pressure boiler.

6. In a steam generating system a super pressure boiler having surfaces heated by the radiant exposure to the fire, and having gravity recirculationthrough the boiler, a high pressure boiler having passages with surfaces heated by the outgoing steam from the super pressure boiler, means for forcing rapid recirculation through the super pressure boiler and its heating surfaces supplemental to its gravity recirculation, and a steam outlet from the high. pressure boiler to the point of consumption; and wherein the super pressure boiler comprises passages constituting a substantially closed circuit with an elevated drum to which the heated surfaces deliver, with a pipe from such drum to said passages in the high pressure boiler and a forced circulation return pipe with pump from said passages back to the lower part of the super pressure boiler.

7. In a steam generating system a tubular boiler with overhead steam-and-water drum from which the steam output is delivered to the point of consumption and said boiler having ascending water tubes exposed to the radiant heat of the fire and delivering to said drum, first downtakes from said drum for gravity recirculation through the boiler, and means for forcing rapid recirculation though the boiler and its heating surfaces supplemental to said gravity recirculation, comprising second gravity downtakes fromthe water space in said drum, such second downtakes extending directly downwardly from such water space so as to be under direct hydrostatic pressure from the water in said drum, a force-pump to which said second downtakes directly lead, said pump being substantially adjacent to the level of the lower ends of said exposed tubes, and receiving water through such downtakes under such direct hydrostatic pressure of said drum, and a system of forced-induced-fiow nozzles connected by piping with the force pump and through which nozzles the force pump discharges into said exposed tubes, one such nozzle for each such exposed tube, and through which tubes, during forced recirculation periods, recirculation is thereby forced from said second gravity downtakes and is supplementally induced from said first gravity downtakes, into the exposed tubes, whereby recirculation is produced at substantially equivalent high rates through all said exposed boiler tubes; said nozzles being so restricted that the recirculated water pressure between the pump and nozzles is substantially greater than the boiler pressure. e

8. In a vapor generating system a tubular boiler with overhead vapor-and-liquid drum from which the vapor output is delivered to the point of consumption and said boiler having ascending liquid tubes exposed to the radiant heat of the fire and delivering to said drum, first downtakes from said drum for primary recirculation'through the boiler, and means for forcing rapid recirculation through the boiler and its heating surfaces supplemental to said primaryrecirculation, comprising secondary gravity downtakes from the liquid space in said drum, such secondary downtakes extending directly downwardly from such liquid space so as to be under direct hydrostatic pressure from the liquid in said drum, a forcepump to which said secondary downtakes directly lead, said pump being substantially adjacent to the level of the lower ends of said exposed tubes, and receiving liquid through such downtakes un der such direct hydrostatic pressure, of said drum, and a system of forced-induced-fiow nozzles connected by piping with the force pump and through which nozzles the force pump discharges into said exposed tubes, one such nozzle for each such exposed tube, and through which tubes, during forced recirculation periods, recirculation is thereby forced from said secondary gravity downtakes and is supplementally induced from said primary downtakes, into the exposed tubes, whereby recirculation is produced at substantial- 14o ly equivalent high rates through all said exposed boiler tubes; said nozzles being so restricted that the recirculated liquid pressure between the pump and nozzles is substantially greater than the boiler pressure.

14-5 7 JAY GOULD COUTANT. 

